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Tobacco BY‐2 cells expressing fission yeast cdc25 bypass a G2/M block on the cell cycle
Author(s) -
Orchard Craig B.,
Siciliano Ilario,
Sorrell David A.,
Marchbank Angela,
Rogers Hilary J.,
Francis Dennis,
Herbert Robert J.,
Suchomelova Petra,
Lipavska Helena,
Azmi Abdelkrim,
Onckelen Harry Van
Publication year - 2005
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2005.02524.x
Subject(s) - mitosis , microbiology and biotechnology , schizosaccharomyces pombe , biology , cell cycle , nicotiana tabacum , cell culture , cyclin dependent kinase 1 , plant cell , cyclin b1 , cell , yeast , biochemistry , saccharomyces cerevisiae , genetics , gene
Summary The mitotic inducer gene from Schizosaccharomyces pombe , Spcdc25 , was used as a tool to investigate regulation of G2/M in higher plants using the BY‐2 ( Nicotiana tabacum ) cell line as a model. Spcdc25 ‐expressing BY‐2 cells exhibited a reduced mitotic cell size through a shortening of the G2 phase. The cells often formed isodiametric double files both in BY‐2 cells and in cell suspensions derived from 35S:: Spcdc25 tobacco plants. In Spcdc25 ‐expressing cells, the tobacco cyclin‐dependent kinase, NtCDKB1, showed high activity in early S phase, S/G2 and early M phase, whereas in empty vector cells CDKB1 activity was transiently high in early S phase but thereafter remained lower. Spcdc25‐ expressing cells also bypassed a block on G2/M imposed by the cytokinin biosynthetic inhibitor lovastatin (LVS). Surprisingly, cytokinins were at remarkably low levels in Spcdc25 ‐expressing cells compared with the empty vector, explaining why these cells retained mitotic competence despite the presence of LVS. In conclusion, synchronised Spcdc25 ‐expressing BY‐2 cells divided prematurely at a small cell size, and they exhibited premature, but sustained, CDKB1 activity even though endogenous cytokinins were virtually undetectable.